Couturier PDF stitcher

Furtherone you may need a PDF stitcher if pdfshuffler doesn't suit your needs: Couturier

You can download the .deb file and install this program. It offers the option of stitching PDF files into one larger file. Direct link

Second direct link

Online editting PDF files

You may need to edit a PDF file and since the many linux apps I know don't offer all the edit options one may need, you could look into:

https://www.pdfescape.com/?noredirect=true

An online editor that works driect from your browser.